The present invention relates to an automotive glazing, which may be a windscreen for a vehicle, especially a road vehicle, e.g. a car. More specifically, the invention relates to an automotive glazing having a glazing component, especially an elongate glazing component such as a seal, dam or mounting profile, attached to one edge of the glazing. In particular, the invention relates to a windscreen having a mounting profile attached to its lower edge, wherein the mounting profile may be for mounting a further component, e.g. one which serves as a water management device and usually also as a rest area for windscreen wipers. Such a further component is generally known as a “cowling”, “water-tray” or “water-box”.
In recent years it has become common practice to provide a rest area for windscreen wipers at least partly below the level of the bonnet or hood of a car. This reduces wind resistance and wind noise, and improves the appearance of the vehicle since the wipers are less prominent, and may even be partially hidden. A component known as a “water-tray” or “water-box” is provided which extends from the lower edge of a windscreen to a position a short way under the bonnet to collect water running off the windscreen and channel it into outlets provided for this purpose at the sides of the vehicle. This process of controlling the flow and discharge of water is sometimes referred to as “water management”.
Preferably the water-tray is flush with the lower edge of the windscreen, so that the wiper blades can pass from the windscreen onto the water-tray without hindrance or damage. This means that the water-tray can only be attached to the windscreen via the lower face (i.e. the inward-facing face) of the windscreen, so that the upward-facing outer face remains clear. Even when the water-tray is not perfectly flush with the windscreen, e.g. because a seal or flange overlaps the windscreen, components by means of which the water-tray may be attached to the windscreen cannot be placed on the upward-facing outer face of the windscreen because the components would protrude excessively from the windscreen.
One example of an arrangement for attaching a water-tray to a windscreen is disclosed in DE 199 39 191. A number of hook-shaped profile pieces are bonded to the underside of the windscreen and the water-tray is clipped directly into the hook-shaped profile pieces by means of prongs extending from the water-tray, the water-tray sealing directly against the windscreen. A disadvantage of this arrangement is that the hooks of the profile pieces and the prongs of the water-tray tend to flex and deform under load, with the result that the water-tray sags below its intended position, and the seal to the windscreen is broken.
Another example of an attachment arrangement is disclosed in U.S. Pat. No. 6,769,700. This arrangement makes use of the vehicle bodywork to provide support for the water-tray, which is attached by means of a reinforced profiled element between the windscreen and the water-tray. This profiled element is first attached to the underside of a windscreen by double-sided adhesive tape. A bead of adhesive, which is used to bond the windscreen to the mounting flange of the vehicle bodywork, is allowed also to extend over part of the profiled element, thereby supporting it. Furthermore, the mounting flange of the vehicle bodywork extends immediately below the profiled element, further supporting it, and preventing it from being deflected downwards when force is applied to the profiled element, usually via the water-tray, which is clipped into position in the profiled element.
However, legislation to improve pedestrian safety requires vehicle bodywork to be readily deformable in the event of an impact between a pedestrian and the front or bonnet of a car. As a result, hard and rigid structures such as the mounting flange for the windscreen are not allowed to extend towards the front of the car at the level of the water-tray, and so can no longer be used to support the water-tray. Without the support of the bodywork, it has been found that the bond provided by double-sided adhesive tape is not sufficient to keep a water-tray mounting profile (i.e. the component referred to as the “profiled element” in U.S. Pat. No. 6,769,700) in position attached to the windscreen.
It is of course important that the water-tray is held tightly against the windscreen and forms a good seal with it, despite the stresses that the water-tray endures in service, e.g. due to thermal expansion and contraction, wind loading, and the pressure of the wipers. The water-tray mounting profile is therefore designed to hold the water-tray securely, i.e. with a high retention force, and so significant force is also required to install the water-tray by clipping it into the mounting profile. Without support from the vehicle bodywork, the bond between the mounting profile and the lower face of the windscreen must withstand all of this installation force.
However, it is not feasible simply to use a stronger adhesive to strengthen the bond between the mounting profile and the lower face of the windscreen, because the glass surface of the windscreen cannot withstand forces beyond a certain magnitude. When this level is exceeded, the glass surface suffers shelling, i.e. it is damaged by the forces transmitted to it by the adhesive with the result that fragments of glass come away from the surface. Furthermore, the water-tray mounting profile is normally mainly composed of polypropylene, to which few adhesives bond satisfactorily in any case.
One solution is offered by WO 2008/138959 and WO 2009/112545. In these publications, a mounting strip is employed which is itself strongly bonded to the windscreen by adhesive and extends along its lower edge. The mounting strip provides a cavity into which the water-tray mounting profile may be inserted. This allows the water-tray mounting profile to be attached later, and so minimises storage and distribution costs. In practice the mounting strip needs to be rigid, and so it is normally fabricated from metal. Metal has the additional advantage that it can be strongly bonded to glass by a wide range of adhesives. While providing sufficient bond strength and support for the water-tray, the use of a metal mounting strip means that this solution adds weight to the assembly. This is undesirable, since vehicle manufacturers are constantly striving to reduce the weight of vehicles in order to improve their fuel efficiency.
A different approach is to modify the water-tray mounting profile to allow the water-tray to be installed with a much lower force, while still providing a high retention force for the water-tray. US 2011/0115261 seeks to achieve this by providing the water-tray mounting profile with a detent or barb. The detent is positioned in a recess in the mounting profile which receives a barbed prong or ridge extending from the water-tray. Although this arrangement does indeed allow installation of the water-tray with less force, it is still found that use of double-sided adhesive tape alone to bond the water-tray mounting profile to the windscreen is unsatisfactory over its expected service life.
Water-tray mounting profiles of the type described in the above documents have become a common way of attaching a water-tray to a windscreen. As previously mentioned, the mounting profiles are reinforced, namely by metal inserts which stiffen the profile, preventing it deflecting under load. However, the lower edge of a windscreen is normally curved, and the mounting profile must adopt this curvature when it is attached to the windscreen. The reinforcement of the mounting profile naturally makes it resistant to bending, and it has been found desirable to use apparatus such as a jig to assist in bending the mounting profile to the desired curvature before offering it up to the lower edge of the windscreen. Such apparatus is machined to correspond to the actual curvature of a particular windscreen (for a particular vehicle), so different apparatus is needed for each different windscreen (for different vehicles), which is expensive.